Downhole oil-water-solids separation

ABSTRACT

A technique facilitates separating fluids and solids and handling the separated solids downhole. A separator system is provided with a separator having a well fluid inlet, an oil stream passage, a water stream passage, and a solids passage. The separator operates to separate well fluid into substantially oil, water, and solids components and those components are directed to the corresponding passages. A flow restrictor may be used in cooperation with the separator to facilitate separation of the well fluid components.

CROSS-REFERENCE TO RELATED APPLICATION

The present document is based on and claims priority to U.S. ProvisionalApplication Ser. No. 61/359,875, filed Jun. 30, 2010 and incorporated byreference herein.

BACKGROUND

Oil well production can involve pumping a well fluid as part oil andpart water, i.e. an oil/water mixture. As an oil well becomes depletedof oil, a greater percentage of water is present and subsequentlyproduced to the surface. The “produced” water can sometimes account formore than 80% of total produced well fluid volume, thus creatingsignificant operational issues. For example, the produced water mayrequire treatment and/or reinjection into a subterranean reservoir todispose of the water and to help maintain reservoir pressure. Treatingand disposing of produced water can be expensive.

One way to address these issues is through employment of a downholedevice to separate oil and water and to re-inject the separated water,thereby minimizing production of unwanted water to the surface. Reducingwater produced to the surface can allow for a reduction of requiredpower, a reduction of hydraulic losses, and a simplification of surfaceequipment. Furthermore, many of the costs associated with watertreatment are reduced or eliminated.

However, successfully separating oil and water downhole and thenre-injecting water is a relatively involved and sensitive process withmany variables and factors that affect the efficiency and feasibility ofsuch an operation. For example, the oil/water ratio can vary from wellto well and can change significantly over the life of the well. Therequired injection pressure also can change over the life of the well.For example, the required injection pressure for the separated watertends to increase over time.

Additional issues arise when the well fluid includes solids, such assand and other particulates which are sometimes mixed in with the wellfluid. The solids tend to be heavier than the oil and separate out withthe water. However, the presence of solids in the water stream cancreate complications downhole, such as clogging. In some applications,the solids separate from the reinjected water stream and tend to clogthe reinjection locations. The ratio of solids in the well fluid/wateralso can change over time which creates greater difficulties in handlingthe solids downhole.

SUMMARY

In general, aspects of downhole oil-water-solids separation provide asystem and method for separating fluids and solids and for handling theseparated solids downhole. The technique utilizes a separator systemhaving a separator with a well fluid inlet, an oil stream outletpassage, a water stream outlet passage, and a solids outlet passage. Theseparator operates to separate well fluid into substantially oil, water,and solids components and those components are directed to thecorresponding passages. A flow restrictor may be used in cooperationwith the separator to facilitate separation of the well fluidcomponents.

BRIEF DESCRIPTION OF THE DRAWINGS

Certain embodiments of downhole oil-water-solids separation willhereafter be described with reference to the accompanying drawings,wherein like reference numerals denote like elements, and:

FIG. 1 is a front elevation view of a well system utilizing an electricsubmersible pumping system in cooperation with a separator system,according to an embodiment;

FIG. 2 is a cross-sectional view of one example of a separator system,according to an embodiment;

FIG. 3 is a cross-sectional view of a portion of the well systemillustrating one example of a flow restrictor, according to anembodiment;

FIG. 4 is a cross-sectional view similar to that of FIG. 3 but showingthe flow restrictor removed from the portion of the well system,according to embodiment;

FIG. 5 is a front elevation view of an alternate example of a wellsystem combined with a separator system, according to an alternateembodiment;

FIG. 6 is a cross-sectional view of one example of a redirector that canbe used with a well system, according to embodiment;

FIG. 7 is a cross-sectional view of a redirector combined with a flowrestrictor for use in the well system, according to an embodiment;

FIG. 8 is a cross-sectional view of an example of a flow restrictorsystem that may be utilized with the well system, according to anembodiment;

FIG. 9 is a cross-sectional view of a flow restrictor systemincorporating a sensor or sensors, according to embodiment; and

FIG. 10 is a cross-sectional view of another example of a separatorsystem in which the well fluid is separated into three components whichprimarily comprise oil, water, and solids, respectively, according to anembodiment.

DETAILED DESCRIPTION

In the following description, numerous details are set forth to providean understanding of the present invention. However, it will beunderstood by those of ordinary skill in the art that the presentinvention may be practiced without these details and that numerousvariations or modifications from the described embodiments may bepossible.

In the specification and appended claims: the terms “up” and “down”,“upper” and “lower”, “upwardly” and “downwardly”, “upstream” and“downstream”; “above” and “below”; and other like terms indicatingrelative positions above or below a given point or element are used inthis description to more clearly describe some embodiments of theinvention. However, when applied to equipment and methods for use inwells that are deviated or horizontal, such terms may refer to a left toright, right to left, or other relationships as appropriate.

Embodiments described herein generally relate to artificial liftsystems, e.g. artificial lift systems in connection with hydrocarbonwells. The embodiments comprise systems and methods for separating wellfluid components, such as oil, water and solids. For example, anembodiment relates to downhole oil/water/solids separation and tomanaging back pressure to manipulate the well fluid componentseparation. One way of controlling separation of oil and water, forexample, is by regulating back pressure applied to the oil stream and/orthe water stream. The back pressure can be controlled by regulating aflow restriction to cause desired throttling of the oil stream and/orwater stream exiting a well fluid component separator. In addition towell fluid component separation, embodiments described herein relate toequipment designed to provide a desired throttling, i.e. back pressure,applied to the outlet streams. The magnitude of throttling can rangefrom completely closed (no flow) to wide open (full flow) depending onthe oil/water/solids content of the well fluid.

Controlling back pressure and related flow can be highly dependent onthe injection zone orientation relative to the producing zone (injectionzone uphole or downhole of the producing zone). Some of the differencesbetween these two orientations relate to injecting uphole where thedevice can throttle and vent to a tubing annulus in a single operation,and injecting downhole where the device may need to throttle the flow“in-line”, i.e. receive the injection flow from tubing, throttle theflow, and then return the flow to another tubing routed toward theinjection zone. In some applications, the diameter of a throttlepassage/opening of a flow restrictor can range from about 0.125 inchesto 1.0 inches.

Referring generally to FIG. 1, a well system 20 is illustrated asdeployed in a wellbore 22. In this embodiment, the well system 20comprises an electric submersible pumping system 24 having a submersiblemotor 26 and a submersible pump 28 driven by the submersible motor 26.The electric submersible pumping system 24 may comprise a variety ofother components, such as a pump vent or intake 30 and a motor protector32. Additionally, the illustrated well system 20 further comprises aseparator 34, such as a centrifugal separator or a cyclone separatordesigned to separate well fluid components. For example, the separator34 may be designed to separate fluid components, e.g. oil and water,fluid and solid components, e.g. water and particulates, or othercombinations of components, e.g. oil, water, and solids. The separator34 may be connected into well system 20 at a variety of locations, suchas the illustrated location above submersible pump 28. However, theseparator 34 also may be positioned upstream from submersible pump 28 tolimit the flow of solids through pump 28.

In the example illustrated, the well system 20 is placed downhole in ahydrocarbon well, such as inside a well casing 36. When placed at adesired location downhole, the submersible motor 26 may be powered todrive both the submersible pump 28 and the separator 34. Duringoperation of this embodiment, well fluid is drawn into pump 28 throughvent 30 and pumped into the separator 34. The separator 34 acceleratesand drives the well fluid mixture in a circular path, thereby utilizingcentrifugal forces to locate the more dense materials, e.g. water andsolids, to a more distant radial position and the less dense fluids,e.g. oil, to a position closer to the center of rotation. In thisexample, an oil stream and a water stream exit the separator 34 andtravel separately along different paths to a redirector 38 whichredirects the water stream and injects it into the surrounding formationwhile directing the oil stream uphole through, for example, a tubing 40to a surface collection location. The separator 34 may be designed toseparate oil, water and solids (see FIG. 10) in which case the solidscomponent of the well fluid is directed by redirector 38 to a desiredlocation. It should be noted that the separator 34 may be used in avariety of locations with or without the redirector 38. For example, theseparator 34 may be utilized to separate oil, water and solidscomponents and then to recombine the solids with the oil stream fordelivery to a desired surface collection location, thus avoidingplugging the water injection zone.

References to water streams, oil streams, and/or solids streams outputfrom the separator 34 refers to streams that have a substantialconcentration of water, oil, and solids, respectively. In other words,the respective streams may contain portions of the other well fluidcomponents and may not be pure in the sense that they contain solelywater, oil, or solids. Depending on the specific application, the wellsystem 20 may comprise various other components, such as packers 42 and44.

FIG. 2 illustrates a cutaway view of one example of separator 34 which,in this case, is a centrifugal type separator. A well fluid mixture isdriven through a well fluid inlet 45 of the separator 34 and into aseparator portion or chamber 46, e.g. a cyclone chamber, of theseparator 34. The components of the well fluid are separated by adivider 48 which defines conduits or passages for carrying the separatedwell fluid components from the separator portion 46. For example, thepassages may comprise an oil passage or conduit 50 and a water passageor conduit 52 which serve as outlets from the separator chamber 46. Thedivider 48 also may separate the well fluid into additional components,such as solids, which are delivered along a separate solids passage orconduit. As illustrated, the oil passage 50 is located further inward ina radial direction with respect to the water passage 52. Back pressuremay be selectively applied to the oil, water, and/or solids streams toaffect the separation process. For example, back pressure on the waterstream through water passage 52 can improve the separation results whenseparating well fluid having a high percentage of oil. For well fluidhaving a higher percentage of water, a higher back pressure for the oilstream through oil passage 50 can similarly improve the oil and waterseparation. Generally, the same back pressure principle applies tocyclone or centrifugal type separators.

Referring generally to FIG. 3, a cross-sectional view of another type ofseparator system 54 is illustrated as having separator 34 to separatethe well fluid components into streams flowing through, for example, oilpassage 50 and water passage 52. It should be noted that the separator34 also may be designed to separate out the solids component which isthen routed along a separate conduit, as discussed in greater detailbelow. In FIG. 3, arrows 56 show a representative path of the oil streamand arrows 58 show a representative path of the water stream. A flowrestrictor 60, e.g. a throttle component, is positioned in the waterpassage 52 in this example. However, an alternate flow restrictor 60 canbe placed in the oil passage 50, or an additional flow restrictor 60 canbe placed in the oil passage 50 so that flow restrictors are in both thewater passage and the oil passage. In this embodiment, the water stream58 flows uphole into the flow restrictor 60.

The flow restrictor 60 may be selected from a number of different typesof flow restrictors, an example of which has an orifice member 62 with aflow through orifice or passage 64. The size of the orifice 64 may varyand the configuration of flow restrictor 60 and orifice member 62enables adjustment of the back pressure in water stream 58. For example,the flow restrictor 60 may be a removable flow restrictor to enableinterchanging with other flow restrictors 60 having a differentthrottling capability, e.g. a different throttle member 62 with a flowthrough orifice 64 having a different size, thus enabling adjustment ofthe back pressure. In other embodiments, the orifice member 62 isremovable and may be interchanged with other orifice members 62 havingorifices 64 of different sizes. The flow restrictor 60 and/or orificemember 62 may be interchanged with the aid of a tool 66 that can belowered downhole to place and/or remove the flow restrictor 60 ororifice member 62. By way of example, the tool used to interchange thedevice may comprise a tool run on a wireline, slickline, coiled tubing,or another suitable conveyance 68. In some applications, slickline canbe the most economical conveyance for changing the throttling. In theexample illustrated in FIG. 3, the oil conduit 50 may be positioned orconfigured to prevent tools lowered by conveyance 68 from inadvertentlyentering the oil passage 50. For example, the oil passage 50 can have anangled portion 70 to prevent the tool 66 from entering the conduit, orthe conduit can be sized so that the tool 66 is not able to enter thepassage.

In some applications, the flow restrictor 60 comprises an orifice member62 having a variable size throttle orifice 64 so that replacement of theflow restrictor 60 is not required to vary the size of orifice 64. Byway of example, the size of the orifice can be adjusted mechanically atthe surface or by tool 66 lowered via conveyance 68, e.g. wireline,slick line, coiled tubing. In other applications, the orifice member 62may have an adjustable orifice 64 which is adjustable via hydraulicpressure directed downhole through a hydraulic line or by an electricmotor controlled by electric signals sent from the surface or from adownhole controller.

As further illustrated in FIG. 3, check valves 72 are located in the oilpassage 50 and/or the water passage 52. The check valves 72 can beutilized to prevent fluid from moving back through the oil passage 50and the water passage 52 into the separator 34. Blocking this potentialbackflow with check valves 72 prevents damage to separator 34.

Referring again to FIG. 1, packers 42, 44 may be used to isolate regionsof the wellbore along a well system 20. By way of example, packers 42and 44 are illustrated as isolating an area where water is to bere-injected into the formation proximate redirector 38 from an areawhere the well fluid is drawn from the formation below the lower packer44. The packer configuration effectively isolates the pump intake 30from the re-injection fluid. Alternatively, the packer 44 can be locatedbelow the submersible pump 28 as long as the water is re-injected abovethe packer 42 or below the packer 44, thereby adequately isolating thearea where the well fluids are produced from the area of the formationwhere the water is injected. A variety of packer configurations may beutilized as long as they are positioned to create isolation betweenproduced fluids and injected fluids.

Well system 20 also may be configured to enable injection of stimulationtreatments downhole. In the embodiment illustrated in FIG. 4, forexample, the separator system 54 is similar to that illustrated in FIG.3 except the flow restrictor 60 has been removed. In the configurationof FIG. 4, stimulating treatments may be pumped down tubing 40 and intoboth the oil passage 50 and the water passage 52. The flow restrictor 60can be replaced with a flow device that prevents treatment fluid fromfollowing along the path of re-injected water. By way of example, arrow74 illustrates a representative path of the stimulating treatment. Thecheck valves 72 prevent the stimulation fluid from traveling into theseparator 34 to avoid causing detrimental effects with respect to theseparator.

Referring generally to FIG. 5, an alternate configuration is illustratedto show re-injection of a water stream to a desired injection zone 76located below a producing zone 78. The submersible motor 26, pump 28,and separator 34 may be connected in a manner similar to that describedwith reference to FIG. 1, and the redirector 38 is connected uphole ofthe separator 34. The redirector 38 is connected to a conduit 80 thatextends downhole to route the redirected fluid through a lower packer82. The lower packer 82 separates producing zone 78 from the injectionzone 76 located below packer 82. In this embodiment, the water streamtravels through conduit 80 and through a tail pipe assembly 84. The tailpipe assembly 84 extends through lower packer 82 and into the injectionzone 76 to enable reinjection of the water component.

FIG. 6 illustrates a more detailed cross-sectional view of an embodimentof redirector 38. Similarly, FIG. 7 illustrates a more detailedcross-sectional view of an embodiment of redirector 38 combined withflow restrictor 60 positioned in a flow restrictor pocket 86. The flowrestrictor pocket 86 is configured to receive the flow restrictor 60. Inthis particular example, the water passage 52 is located radiallyoutside of the oil passage 50 based on the centrifugal oil/waterseparation. The oil passage 50 extends from the downhole redirector 38,through the redirector, and uphole past the redirector until it connectswith tubing 40, e.g. production tubing/coiled tubing. The water passage52 extends from below the redirector 38 and into the redirector 38. Thewater passage 52 merges into a water passage 88 which connects the waterpassage 52 with the flow restrictor pocket 86. In the illustratedembodiment, the water passage 88 extends in a direction substantiallyperpendicular to the water passage 52 so the water stream flows througha sharp turn, e.g. a 90° turn. However, the angle of the turn can varyand in some applications it may less sharp, e.g. 45° or more sharp, e.g.135°. A re-injection passage 90 is connected between the flow restrictorpocket 86 and an appropriate passage, e.g. conduit 80, to route thewater component of the well fluid to the desired injection zone 76.

With additional reference to FIG. 8, an embodiment of the flowrestrictor 60 is illustrated. In this embodiment, the flow restrictor 60comprises a body 92 which defines therein an upper inner chamber 94 anda lower inner chamber 96. The upper inner chamber 94 and the lower innerchamber 96 are divided by a flow restriction, such as flow restrictionorifice member 62 having the flow passage/orifice 64 by which fluid flowis throttled. The orifice member 62 and the flow restrictor body 92 canbe the same part or two different parts which are fit together. Theentire flow restrictor 60 and/or flow restrictor orifice member 62 maybe fixed or removable depending on the well fluid separationapplication.

In the embodiment illustrated, the flow restriction orifice 64 oforifice member 62 has a narrower diameter than the diameter of upperinner chamber 94 or lower inner chamber 96, however the diameter of theorifice 64 could be essentially the same as the diameter of either theupper chamber 94 or the lower chamber 96. Additionally, one or morepassages 98 are located in the flow restrictor body 92 and hydraulicallyconnect the upper chamber 94 with a region external to the flowrestrictor 60. Another passage 100 is located on a downhole end of theflow restrictor 60 and provides a flow path which enables communicationwith the bottom of orifice member 62 through lower inner chamber 96.

When the flow restrictor 60 is positioned within flow restrictor pocket86, the passages 98 allow fluid to pass from the water passage 88,through the passages 98, and into the upper inner chamber 94. The fluidthen flows through the restrictor orifice 64 of orifice member 62, andinto the lower inner chamber 96. From the lower inner chamber 96, thefluid, e.g. water, flows through passage 100 and out of flow restrictor60 for re-injection into a desired zone, e.g. injection zone 76. Aplurality of seals 102, e.g. O-ring seals, may be mounted about body 92to form a seal with the interior surface of flow restrictor pocket 96.In a variety of applications, the flow restrictor 60 may be removable.Additionally or alternatively, the orifice member 62 can be constructedas interchangeable or adjustable to enable adjustment with respect tothe size of flow passage 64. It should be noted that the flow restrictor60 can have many internal configurations that enable the desiredrestriction/throttling of fluid flow to facilitate separation of wellfluid components.

When removable, the flow restrictor 60 may comprise an attachment member104 designed to facilitate engagement with tool 66 for placement andretrieval with respect to the flow restrictor pocket 86. As notedearlier, the tool 66 can be connected to a variety of conveyances 68,e.g. wireline, slick line, or coiled tubing.

In many applications, the separation techniques applied and the flowrestrictor selected depend on parameters/characteristics related to thewell fluid, e.g. well fluid content. For example, the content of thewell fluid can be useful in determining the appropriate techniques forseparating, producing, and re-injecting the various well fluidcomponents. In some applications, a sensor 106 can be located downholeto determine selected parameters of the well fluid, such as theoil/water/solids ratio in the well fluid, as illustrated in FIG. 9. Datafrom sensor 106 may be transmitted uphole in many ways, e.g. electricsignals over a wire, fiber optic signals, radio signals, acousticsignals, wireless transmission techniques, and other suitable datatransfer techniques. Alternatively, the signals may be transmitted to adownhole processor 108. The downhole processor 108 can be used toprovide instructions to, for example, a motor coupled to an adjustableorifice member 62 to set a certain orifice size or to perform otherdownhole functions. Depending on the application, the sensor 106 can belocated downstream from the well fluid intake of the separator 34,inside the separator 34, inside the redirector 38, inside the flowrestrictor 60, outside of the separator 34 and downhole from the wellfluid intake 30, outside of the separator 34 and uphole from the wellfluid intake 30, outside the separator 34 and at the same level as thewell fluid intake 30, downstream from the well fluid inlet 30, upstreamfrom the separator, or at other suitable locations.

Referring again to FIG. 9 an example of the flow restrictor 60 isillustrated as having sensor 106 located in the upper inner chamber 94.In an alternate embodiment, the sensor 106 may be located in the lowerinner chamber 96; or multiple sensors 106 may be located in the upperinner chamber, the lower inner chamber, and/or other desired locations.Depending on the desired acquisition of information regarding the wellfluid, the sensor 106 may be designed to sense a variety of parameters,such as temperature, flow rate, pressure, viscosity, oil/water ratio, orother desired parameters. Additionally, the sensor or sensors 106 may beused in cooperation with a telemetry pickup 110 which is integrated intothe redirector 38 or into another suitable component of the well system20. The sensor 106 is able to communicate with downhole processor 108 orwith another suitable data gathering system via an appropriate telemetrysystem, e.g. an electrical contact or “short-hop” telemetry system. Asdiscussed above, the information obtained from sensor 106 also may beused to adjust the size of orifice 64. For example, orifice member 62may comprise an adjustment mechanism 111 which is mechanically,hydraulically, electrically, or otherwise adjustable. In one example, atool may be lowered on a suitable conveyance 68 to mechanically actuateadjustment mechanism 111, thus changing the size of orifice 64.

Referring generally to FIG. 10, another embodiment of separator 34 andseparator system 54 is illustrated. In this embodiment, the separator 34is designed to separate the well fluid into additional components. Forexample, the separator 34 may be designed to separate well fluid intooil, water, and solids, e.g. particulates, to provide beneficialseparation and production results. A factor in the long term, successfulapplication of downhole fluid separation technology is maintaininginjectivity into the injection zone, e.g. zone 76. During a productionoperation, reductions in injectivity can be caused by solids, e.g.particulates, which are carried to the injection zone, e.g. zone 76,following oil and water separation. The accumulation of solids on thesand face of the injection zone can reduce the injectivity. Maintainingthe injectivity index as close as possible to the initial injectivityindex for as long as practical can be beneficial to continued operationof the downhole fluid separation systems. Production can be improved bylimiting the amount of solids deposited at the injection zone alone orin combination with injection zone stimulation intervention.

The embodiment of separator 34 illustrated in FIG. 10 is designed toprovide an additional stream of discharge for the solids. The stream canbe used to direct the solids away from the water injection zone 76. Insome applications, the stream of discharge for the solids can berecombined with the produced oil component of the well fluid so as toleave the injected stream of water relatively free of solids.

As discussed above with respect to separator 34, separation of the oilcomponent, water component, and solids component can be achieved byrotating, dynamic separators, e.g. cyclone or centrifugal separators,operating according to the principle of density separation using theforces created from rotation. When the well fluid is rotated, theheavier phase/component is separated to the outer radius of rotation.For example, the heavier solids may be separated to a radially outerregion, while the lighter water is separated to an intermediate region,and the lighter oil is separated to a region closer to the core ofrotation. This radially centric oil component (possibly with someremaining water and/or solids) is discharged as the production stream.

Referring again to the embodiment illustrated in FIG. 10, the separator34 comprises a solids passage 112 through which a solids stream having ahigh concentration of solids is discharged. As illustrated, the solidspassage/discharge 112 is located at a position which is a radialoutlying position relative to the water passage 52 and the oil passage50. Passages 50, 52 and 112 serve as outlets from separator region 46 asthe streams enter divider 48. In this example, the solids are theheaviest components and the cyclone/centrifugal separation separates thesolids (with some water as a carrying fluid) to the outermost radius ofthe separator portion 46. As described above, the oil is lightest and isseparated to the core of the rotation to create an oil stream. Amajority of the water is separated to an intermediate location betweenthe oil component and the solids component and is relatively free ofsolids. This water stream, which is relatively free of solids, may bedischarged to the desired injection zone, e.g. injection zone 76, viatechniques described above. Re-injecting the water stream at injectionzone 76 avoids the potential for clogging the injection zone 76 and thusavoids damage to the injection zone. The outermost component of the wellfluid is the solids component which contains the highest proportion ofsolids, and this solids component can be routed to a recombinationregion 114 and recombined with the oil stream as production flow in, forexample, tubing 40.

In operation, a well fluid mixture is driven into the separator chamber46, e.g. a cyclone/centrifugal chamber, of the separator 34 bysubmersible pump 28 or another suitable pump of pumping system 24. Thewell fluid flows into separator portion 46 of separator 34 through awell fluid inlet 116. Within separator portion 46, the components of thewell fluid are separated into the oil, water, and solids componentswhich primarily comprise oil, water, and solids, respectively. Streamsof primarily oil, water, and solids are then split into componentstreams by divider 48, and the respective component streams are routedthrough the corresponding oil passage 50, water passage 52 and solidspassage 112. The well fluid components may be directed through acorresponding oil stream outlet 118, water stream outlet 120 and solidsoutlet 122 of divider 48 to appropriate flow paths downstream. The waterpassage 52 is radially outward relative to oil passage 50, and thesolids passage 112 is radially outward relative to water passage 52. Byway of example, the oil passage 50, water passage 52, and solids passage112 may be in the form of concentric conduits which route the respectivewell fluid components to desired locations downstream. For example, thecomponent streams may be routed to an appropriate redirector 38 and/orthrough appropriate flow restrictors 60.

As described with respect to the various well system embodiments above,the separation of well fluid components, e.g. the separation of oil,water, and solids components, can be improved by manipulating the backpressure on the various well fluid component streams. In manyapplications, the desired back pressure can be accomplished by providingremovable flow restrictors, removable orifice members, and/or adjustableorifices placed in the oil/solid stream and/or the water stream.However, the back pressure can be created with a variety of devices andwith respect to various combinations of the well fluid component streamsto achieve desired production results. The flow restrictor, for example,can be placed in the oil/solid stream, the oil component stream, thewater component stream, and/or the solids component stream.

Although only a few embodiments of the present invention have beendescribed in detail above, those of ordinary skill in the art willreadily appreciate that many modifications are possible withoutmaterially departing from the teachings of this invention. Accordingly,such modifications are intended to be included within the scope of thisinvention as defined in the claims.

1. A downhole device, comprising: a separator system, having: aseparator comprising a well fluid inlet, an oil stream passage, a waterstream passage, and a solids passage; and a removable flow restrictorlocated in at least one of the water stream passage, the oil streampassage, or the solids passage to facilitate separation of well fluidcomponents.
 2. The downhole device of claim 1, wherein the removableflow restrictor has a fixed throttle orifice member having a flowpassage, the size of the flow passage being changed by interchangingflow restrictors.
 3. The downhole device of claim 1, wherein theremovable flow restrictor has a removable throttle orifice member havinga flow passage, the size of the flow passage being changed byinterchanging removable throttle orifice members.
 4. The downhole deviceof claim 1, further comprising a pumping system having a submersiblepump, wherein the water stream passage opens up into a wellbore at apoint farther downhole than the submersible pump.
 5. The downhole deviceof claim 1, wherein the removable flow restrictor is removable by adownhole tool relayed downhole by a conveyance.
 6. The downhole deviceof claim 1, wherein the separator is a cyclone separator.
 7. Thedownhole device of claim 1, wherein the separator is a centrifugalseparator.
 8. The downhole device of claim 1, wherein the separatorsystem further comprises a sensor that senses a parameter of flowingfluid.
 9. The downhole device of claim 8, wherein the sensor is locateddownstream from the well fluid inlet.
 10. The downhole device of claim8, wherein the sensor is located inside the separator.
 11. The downholedevice of claim 8, wherein the sensor is located upstream from theseparator.
 12. The downhole device of claim 1, wherein the removableflow restrictor has a throttle member with a selectively variableorifice.
 13. A method of separating fluids and solids downhole,comprising: placing a separation system downhole, the separation systemcomprising a separator having a well fluid inlet, an oil stream outletpassage, a water stream outlet passage, and a solids outlet passage, theseparator system further comprising a flow restrictor pocket located inthe oil stream outlet passage or the water stream outlet passage;determining a parameter of a downhole well fluid; selecting a degree offlow restriction based on the determination and selecting acorresponding flow restrictor; and placing the selected flow restrictorin the flow restrictor pocket.
 14. The method of claim 13, furthercomprising varying the flow restriction by removing the flow restrictorfrom the separator while the separator is downhole and then placing adifferent flow restrictor having a different throttle into the separatorwhile the separator remains downhole.
 15. The method of claim 13,wherein determining comprises determining with a sensor located downholewithin the separator system.
 16. The method of claim 15, furthercomprising locating the sensor inside the flow restrictor.
 17. A methodof preparing a downhole fluids and solids separation system, comprising:constructing a separator with a separation portion in communication witha fluid inlet, the separation portion also being in communication with adivider having an oil stream passage, a water stream passage positionedradially outward from the oil stream passage, and a solids passagepositioned radially outward from the water stream passage; andpositioning a flow restrictor in cooperation with the separator toenable selective manipulation of the separation of water and oil. 18.The method of claim 17, further comprising deploying the separatordownhole into a wellbore; and separating oil, water, and solids fordischarge through the oil stream passage, the water stream passage, andthe solids passage, respectively.
 19. The method of claim 18, furthercomprising using a downhole pumping system to pump the separated oil toa surface location.
 20. The method of claim 19, further comprisingreinjecting the separated solids back into the separated oil above thedownhole pumping system; and delivering the separated solids to asurface location.